How to know if your joints are lubricated
If you've ever had a relative who has gone through joint replacement surgery, you know it's not a pleasant experience. A good question to ask is, how do you avoid the need to get a joint (or joints) replaced in the first place?
One of the problems that artificial joint engineers deal with is keeping artificial joints lubricated. They actually look at combinations of material that wear less so that the joint lasts longer thus avoiding the need to get it replaced, again.
Now if artificial joint engineers have this problem, it might make sense to wonder if the problem with our natural joints being wrecked isn't due to a natural lubrication failure. The question we can then ask is, how are our joints lubricated? If we know this then we can work at keeping them lubricated.
In a car there is generally a red light that goes of when a sensor detects that oil pressure is low. If oil pressure is low while the engine is running that generally means that there isn't enough oil in the engine. That in turn means that if the condition persists, i.e. if you don't put more oil in the engine, you're going to wreck the engine. And engines are expensive.
With the human body, we don't necessarily have the equivalent of an engine, we have muscles which don't really need lubrication. However, we also have joints and one supposition we can make is that joint lubrication is important.
If we get a lubrication failure in a joint, and that failure goes on for long enough, the joint will no longer function. And we'll have to get it replaced.
The question we can now ask is, does our body have the equivalent of a car engines red low oil pressure warning light?
Note that in a car the warning light is exactly that, a warning light. If we don't know what it means we might just ignore it. A little while later the car stops running and we wonder if perhaps that was what the red light was trying to warn us about.
Now what happens if the red light, for whatever reason doesn't work? Then the same thing can occur. We can get a situation where there's low oil pressure meaning a lack of oil. The problem goes untreated because we don't know about it. The engine dies as a result.
I bring this scenarios up because their equivalents are both possible with respect to the body. We may get the warning signs and ignore them and thus require a joint replacement. Or the warning light doesn't work and thus at some point we require a joint replacement.
Knowing the benefits of having a warning light, we'll want to make sure that first of all it works and second of all we do something in response when the warning light turns on.
If the light doesn't work, we fix it. If then the light turns on, we put more oil in the engine.
With a car engine, in part it's the movement of the engine that pumps oil around the engine. The engine has to be working for the lubrication system to work and that kind of makes sense. If the engine is off it doesn't need to be lubricated. (That being said, when I was in the army, there was a problem with vehicles left to sit for too long. As a result, seals and gaskets would dry out. And so a warm up was required to get the seals working properly.)
One of the things that artificial joint engineers have found out is that one type of lubrication method for synovial joints requires movement or is driven by movement. This method of lubrication is called hydrodynamic lubrication and requires high speeds to work. So for example, running, or walking quickly, in either case with a fast pace could utilize this method of lubrication.
But running or walking with a fast pace (take shorter steps to quicken the pace) might not guarantee that your joints are being lubricated. And this avoids the question of the red warning light. How do you know when your joints are not being lubricated?
Before going on to warning lights for the body, it can help to have an understanding of why joints need to be lubricated and how they are lubricated. If joints are kept lubricated, that means that articulating surfaces can "adjust" relative to each other. That in turn means that tension within the joint capsule is always evenly (or appropriately) distributed throughout the joint capsule. That in turn means that connected connective tissue structures can distribute forces from the joint capsule to other connected parts of the body.
As an example, if you press in on one part of a balloon, the skin of the balloon distributes the stress throughout the rest of the balloon. With a bicycle wheel, spokes provide a network for distributing tension.
If the balloon breaks, it can't hold air and that in turn means that it can no longer redistribute tension throughout its fabric. If a bicycle wheel spoke is broken, it's not necessarily as catastrophic, unless the number of spokes is the exact minimum required for the wheel to function. In this case, when a spoke breaks the wheel is effectively rendered useless.
With a synovial joint, lubrication means that that the joint capsule can distribute forces.
Note that with a balloon, when it is popped it becomes useless. With a joint capsule, the capsule could work as a container for synovial fluid. If there is a lubrication failure the result could be a ruptured joint capsule. And that's when a new joint is required.
So how could a lubrication failure result?
Our body is fairly heavy. It's made up of lots of joints. Those joints can be subjected to different forces depending on whether or not they are bearing weight. In addition, those forces can increase in activities like running or weight lifting. In all of those situations, lubrication has to be maintained.
One simple way to deal with this is to use muscle activation to increase joint capsule tension when required. As an example of what this could be like, you've possibly ridden a bicycle or been in a car when tire pressure has been low. You can feel the bumps as the rim of the wheel or wheels bottoms out against the road. With higher, or appropriate, tire pressure, this doesn't occur.
Muscle activation offers a simple mechanism for adjusting joint capsule tension and thus synovial fluid pressure so that lubrication is maintained. With sufficient synovial fluid pressure, joint surfaced can be prevented from rubbing against each other which means that the joint capsule can continue to distribute stresses.
The beauty of this system is that muscles provide proprioceptive feed back when they are active.
If muscles aren't active (or aren't active enough), you don't get any feedback. And this may be one reason why "floppy" people may be in more danger of needing joint replacements. They don't have enough muscular activation to keep their joints lubricated. And at the same time, their equivalent of an oil pressure warning light isn't working. They can't feel their body and as a result don't realize when they are messing up their joints.
So what kind of signals can we expect when muscles aren't working as required to keep joints lubricated? Pain may be one way that our brain is telling us something is wrong. A lack of function or flexibility might occur when the brain deliberately inhibits a particular movement because it thinks a joint is in danger.
Being more proactive, if we learn to feel our body, i.e. feel muscle activation and connective tissue tension, both of which are proprioceptive signals, we can get a fairly good indication that our joints are being lubricated. Note that a lack of sensation or excessive connective tissue tension are other signals that can indicate a problem. Note that this is a good thing in one way. At least you are getting some signal and that means you can act on it.